Dental matrix adapting and tooth separating device



' June 23, 1959 C. E. CROWLEY DENTAL MATRIX ADAPTII JG AND TOOTH SEPARATING DEVICE Filed Jfiiy' 19, 1955 United States Patent 2,891,313 Patented June 23, 1959 DENTAL MATRIX ADAPTING AND TOOTH SEPARATING DEVICE Carolyn E. Crowley, New York, N.Y. Application July 19, 1955, Serial No. 522,973 3 Claims. (CI. 32-63) This invention concerns a novel and useful dental matrix adapting and tooth separating device that readily conforms a matrix band to the proximal surface of a tooth also producing a selected separation of the tooth from the adjacent tooth, thereby compensating for the thickness of the matrix, by which actions a better filling with proper seal along the margins and good interdental contact is produced.

As is known, in making a restoration or filling involving the proximal surface, i.e.-side of a tooth, a pliable matrix is placed about the prepared cavity thereby providing a lateral wall to such a cavity against which the filling material or impression material can be packed. Without such a matrix, the soft material such as amal 'gam alloy or silicate cement would flow out the open proximal side of the cavity. When such a matrix is applied to the tooth, it is found that the natural bulge in the upper portion of the tooths crown does not allow the matrix to keep in uniform contact with the proximal surface. Though it may fit snugly at the bulge, it is naturally looser below it where the tooth tapers inwardly. Even a matrix that is made to supposedly compensate for this anatomical difficulty cannot actually be depended upon since there is both a wide variety of degrees of taper and prominence of bulge in teeth. Indeed, the apparent adaptation of the matrix in this region may be quite deceptive; and when filling material is inserted under the usual condensing pressure, the matrix will yield allowing for an oozing along its interior borders. If there is no adjacent tooth, the dentist can carefully scrutinize the completely visible margins and he can then readily trim away such excess of material. If there is an adjacent tooth however, the dentist cannot see these inner margins. When he removes the matrix after the filling hasset, he may find this excess by feel with an instrument or by-X-rays; but it is now a hardened part of the filling, It is a tedious and time-consuming processjto strip away this excess; Should it remain however, it' 'may become a retentive area for finely divided food part cles thereby-encouraging recurrent decayj 'or again, it can" cause a localized gingivitis and bone resorption. Hence, it is necessary. toensure that this area of matrix belqw-thebulge or contact point ofthe toothis firmly adapted to the tooth and cavity margins during the filling operation. l

.wThe greativarietyLof devices .introducedto. meet. .this problem indicates its importance and their number indi rectly attests to the lack of any simple, practical solution to date. Some of these attempted solutions have included pre-contoured bands whose inability to meet the variety of anatomy encountered has been indicated. Others employed devices such as encircling wires that could be twisted or screwed tight about a matrix. A variety of yoked instruments having terminal prongs that engaged the tooth from the buccal and lingual sides and could then be screwed closed to exert a conforming pressure to the matrix have also appeared. These actually engaged the teeth rather than the matrix, with the unfortunate result that maximum separation of the teeth was necessary in order to drive the prongs far enough through the interdental space to meet at and support the center of the matrix. Besides the dilficulty of adjusting the screw mechanisms when used on posterior teeth, the yoke extending across the area of operation obscured the field and made it difiicult to operate. Indeed, the yoke might accidently be pushed, causing it to exert a lever aged rotating action on the prongs, producing a sudden further wedging of teeth that was surprising and painful. Other devices, while theoretically serving their purpose, were too cumbersome to apply and remove in actual use in narrow confines of the mouth. Often their manipulation disturbed the matrix, producing defects and cracks in the newly set filling. For these and other reasons, such devices were unsatisfactory.

The purpose of the present invention is to make a matrix adapting and tooth separating device that would avoid these deficiencies and could readily be applied to conform a matrix in conjunction with the usual matrix retainer or without it, as the situation determined.

A further object of this invention is to provide a device that produces a controllable and selective separation of the teeth without the use of screws and other mechanical intermediaries in the device, thereby preserving the valuable direct tactile sense of the dentist in applying and removing said device.

Another object of this invention is to ensure that the pressure for adapting the matrix is a physiological type of pressure resulting from the reciprocal action of the adjacent tooth, thereby avoiding rigid and arbitrary mechanical force. 7

Another object of this invention is to develop simultaneously a conforming pressure which adapts a matrix and also separates the two teeth to ensure that upon re moval of the device and the matrix the filling will be compensated to the extent of the thickness of the matrix, thus restoring proper contact between the filled tooth and the adjacent tooth.

Another object of this invention is to provide a device that is easily removed, thereby avoiding disturbance to the matrix and the newly placed filling.

Another object of this invention is to provide a device that will not injure the sensitive interdental papilla of the gum. a 1

Another object of this invention is to provide a device that is. equally applicable to the teeth in both upper and lower jaws, on both left and right sides, and from either the buccal or lingual sides of the interdental space.

Another object of this invention is to provide a device that in use lies outside of the operative area and therefor leaves the operative field unobstructed.

Another object of this invention is to provide a device having no moving parts, thereby eliminating mechanical breakdown and the need for maintenance, and also ensuring complete and ready cleaning and sterilization without disassembling of the device.

' Objects and advantages other than those set forth will be apparent to those skilled in the art from the following description when read in' conjunction with the accompanying drawings in which:

Figure 1 illustrates a general view of an embodiment of the present invention showing the salient features of its structure;

Figure 2 illustrates a plan view of the device adapting a matrix to a cavity on the proximal side of the tooth;

Figure 3 is a side elevation showing the device in use.

Referring more particularly to Figure 1, the device is shown as a rod like element, tapering from a scored rectangular wider handle end 1 to a narrow tip 4. The length is shaped to conform to the proximal surface of a tooth. The rod has a substantially flattened surface 2 which rests against the matrix band and a substantially convex surface 3 which rests against the side of theada jacent tooth. I

Referring to Figures 2 and 3, a description of the device in use shows that after a cavity 8 involvingithe prox imal surface of a tooth is prepared for filling, a .rnatrix 'band 5 is placed about the proximalsurface to provide a wall to sustain the filling material. The matrix is usually supported by a standard matrix holder shown in Figure 3.

'With the matrix in position, the present device is now introduced so as to adapt the matrix prior to filling. This rod like device is grasped by its rectangular scored end and inserted in an essentially horizontal directionat approximately a right angle to the interdental space 6. The narrow tip 4-is inserted first, oriented so that the flattened side 2 rests against the matrix. This flattened surface slides easily along the smooth metal surface of the matrix. The ease of insertion is facilitated by the opposite surface 3 sliding along the proximal surface 7 of the adjacent tooth with reduced friction, owing to the small surface contact presented by this convex side of the rod. As the adapter is progressively introduced, the slightly rounded but acute angle at the lower end of the flattened side '2 engages the crevice between the interdental papilla and the tooth and gently deflects the papilla '11 under the inclined inferior surface of the rod, as shown in Figure 3. This both protects the papilla from direct impingement and allows the adapter to rest against the least sensitive and strongest area of the gingiva-the tissues and fibrous ligaments at the neck of the tooth. The device is introduced gradually so that the wedging action develops a reciprocal pressure from the slight separation of the two teeth. This pressure is essentially a function of the elasticity of the teeths supporting ligaments and bone, and hence has a natural or physiological quality that not only prevents damage to the teeth through overstraining, but also ensures that the filling being made will have a proper contact with the adjacent tooth since it will be based upon this natural measure of the two teeths tendency to displacement. This same pressure, acting along the contoured rod, adapted the matrix against the edge of the floor of the cavity from its buccal to its lingual aspect. The teeth are also separated at the contact point 9 as already indicated, The dentist has complete control over the adapter and. is guided by direct tactile sense as to the teethsresponse in regard to pressure exerted. This pressure in turn keeps the rod in position during filling, making it self-retaining.

The filling material is now placed in the cavity and condensed. The adapters flattened surface keeps the matrixtight against the cavity and prevents any oozing offilling material below the matrix band. The device also facilitates the filling operation by leaving the operative area unobstructed, since the adapter lies entirely below or cervical to the occlusal surface of the tooth. After the filling undergoes initial setting, the adapter is gently withdrawn. The same features of surface and contour that made for ease of insertion allow its withdrawal without disturbing the matrix or filling. The matrix is next removed and the filling given its preliminary carvingand finish.

As is already indicated, this invention may also be used as a tooth separating device alone. It is understood that the invention is not confined to the particular embodiment described but is susceptible tossuch changes .and

modifications which shall define no material departure from the salient features of the invention as expressed in the appended claims.

It is claimed and desired to secure by Letters Patent:

1. A dental matrix adapting and tooth separating device consisting of a single tapered and curved resilient rodlike elementinsertible at substantially aright angle into an interdental space cervical to the contact point of the teeth bordering said interdental space, said rod like element traversing and occupying said interdental space from its buccal throughsits lingual aspect; a gripping means on the wider handle end of said rod like element for manipulation of same;.said"wider end portion at an angle to the narrow tip portion of said rod like element thereby providing when in place a broad support for a cotton roll or gauze pack and further providing, in combination with said gripping means, retention of cotton roll or gauze pack.

2. A dental matrix adapting and tooth separating device-consisting of a single curved rod like element tapering from a wider, handle end to a narrow tip gripping means in said handle end; a substantially flattened .side on said rod; a narrower substantially convex side opposite thereto; mutually inclined upper and lower surfaces in said rod; angles acute and equal, having slightly rounded edges formed by the junction of flattened side with the said upper and lower surfaces; said .rod like velement being insertable at substantially a right angle into an interdental space cervical to the contact point ofthe teeth bordering said interdental space; said rod like element traversing and occupying said space from its buccal through its lingual aspect.

3. A dental matrix adapting and tooth separating aevi'ce'consisting of a single resilient rod like element tapering from a wider, handle end to a narrow tip. gripping means in said handle end; a contour in said resilientro'd adaptively conforming through wedging pressure to'the proximal surface'of a tooth from its buccal through :its lingual aspect; a substantially flattened side on said rod; a narrower substantially convex side opposite thereto; mutually inclined upper and lower surfaces in .saidirod; angles acute and equal, having slightly rounded edges formed by the junction of flattened side with the said upper and lower surfaces; said rod like element being insertable at substantially a right angle into an interdental space cervical to the contact point of the teeth bordering said interdental space; said rod like element traversing and occupying said space from its buccal through its lingual aspect.

References Cited inthe file of this patent UNITED STATES PATENTS 532,722 Dennis "Ian. 15, 1895 812,189 Dorr Feb. 13, 1906 2,536,669 ThauJensen Jan. 2, 1951 2,782,503 Thompson Feb. 26, 1957 FOREIGN PATENTS 627,654 Great Britain Aug. 12, 1949 OTHER REFERENCES W.5'A. Woodward: Separators, Dental Cosmos 1886, p.28 

